Package substrate and package structure using the same

ABSTRACT

A package substrate is provided. The package substrate includes a base layer having a first surface and a second surface opposite to the first surface, a plurality of through holes penetrating the base layer, a first metal layer disposed on the first surface, and comprising an encircling portion and a plurality of upper pads arranged separately, wherein the encircling portion surrounds the upper pads to form a trench between the encircling portion and the upper pads, and a second metal layer disposed on the second surface and comprising a plurality of bottom pads arranged separately, wherein the bottom pads are electrically connected to the upper pads via the through holes respectively. The through holes are positioned under the upper pads and the encircling portion of the first metal layer is electrically floating.

This application is a continuation application of co-pending U.S. application Ser. No. 15/073,707, filed Mar. 18, 2016, which claims the benefit of U.S. Provisional application Ser. No. 62/134,577, filed Mar. 18, 2015, the present disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The disclosure relates in general to a package substrate and a package structure using the same, and more particularly to a package substrate having trenches and a package structure using the same.

BACKGROUND

In an ordinary package structure, the chip is packaged using a resin to avoid the light being laterally emitted from the chip. However, during the manufacturing process of the package structure, the resin is not easy to control, and outflow of the resin may arise easily. Besides, when the package substrate is coated with a solder paste containing a flux, gas bubbles may easily be generated and the soldering quality would deteriorate accordingly.

Therefore, it has become a prominent task for the industries to provide a package substrate capable of resolving the above problems.

SUMMARY

The disclosure is directed to a package substrate having trenches and a package structure using the same. Through the design of forming trenches on a front side and forming a specific heat dissipation structure on a rear side of the package substrate, the outflow of resin can be effectively avoided and the soldering quality can be increased.

According to one embodiment of the disclosure, a package substrate is provided. The package substrate includes a base layer having a first surface and a second surface opposite to the first surface, a plurality of through holes penetrating the base layer, a first metal layer disposed on the first surface, and comprising an encircling portion and a plurality of upper pads arranged separately, wherein the encircling portion surrounds the upper pads to form a trench between the encircling portion and the upper pads, and a second metal layer disposed on the second surface and comprising a plurality of bottom pads arranged separately, wherein the bottom pads are electrically connected to the upper pads via the through holes respectively. The through holes are positioned under the upper pads and the encircling portion of the first metal layer is electrically floating.

According to another embodiment of the disclosure, a package structure is provided. The package structure comprises a package substrate at least one chip, a reflective layer and a light transmissive layer. The at least one chip is disposed on the package substrate and electrically connected to the upper pads. The reflective layer is disposed on the package substrate and having a portion filled into the trench, wherein the reflective layer covers the chip and exposes at least a portion of an upper surface of the chip. The light transmissive layer covers the exposed portion of the upper surface of the chip.

According to another embodiment of the disclosure, a package structure is provided. The package structure comprises a package substrate at least one chip, a reflective layer and a light transmissive layer. The at least one chip is disposed on the package substrate and electrically connected to the upper pads. The reflective layer is disposed on the package substrate and having a portion filled into the trench, wherein the reflective layer surrounds a lateral surface of the chip and exposes at least a portion of an upper surface of the chip. The light transmissive layer covers the exposed portion of the upper surface of the chip and at least extends between the reflective layer and the lateral surface of the chip.

The above and other aspects of the disclosure will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment (s). The following description is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a package structure according to an embodiment of the present disclosure.

FIG. 2A shows a cross-sectional view of a package structure along a cross-sectional line A-A′ of FIG. 1 according to an embodiment of the present disclosure.

FIG. 2B shows a cross-sectional view of a package structure along a cross-sectional line A-A′ of FIG. 1 according to another embodiment of the present disclosure.

FIG. 3A shows a bottom view of a package structure according to an embodiment of the present disclosure.

FIG. 3B shows a bottom view of a package structure according to another embodiment of the present disclosure.

FIGS. 4A-4C show an embodiment of the manufacturing process of the package structure of the present disclosure.

FIGS. 4D-4E show another embodiment of the manufacturing process of the package structure of the present disclosure.

DETAILED DESCRIPTION

A number of embodiments of the present disclosure are disclosed below with reference to accompanying drawings. However, the structure and content disclosed in the embodiments are for exemplary and explanatory purposes only, and the scope of protection of the present disclosure is not limited to the embodiments. Designations common to the accompanying drawings and embodiments are used to indicate identical or similar elements. It should be noted that the present disclosure does not illustrate all possible embodiments, and anyone skilled in the technology field of the disclosure will be able to make suitable modifications or changes based on the specification disclosed below to meet actual needs without breaching the spirit of the disclosure. The present disclosure is applicable to other implementations not disclosed in the specification. In addition, the drawings are simplified such that the content of the embodiments can be clearly described, and the shapes, sizes and scales of elements are schematically shown in the drawings for explanatory and exemplary purposes only, not for limiting the scope of protection of the present disclosure.

FIG. 1 shows a top view of a package structure 100 of an embodiment of the present disclosure. FIG. 2A shows a cross-sectional view of a package structure 100 along a cross-sectional line A-A′ of FIG. 1 according to an embodiment of the present disclosure. FIG. 2B shows a cross-sectional view of a package structure 100 along a cross-sectional line A-A′ of FIG. 1 according to another embodiment of the present disclosure. It should be noted that some elements of FIG. 1 are omitted, such that the relationships between other elements disposed on the package substrate 10 may be clearly illustrated.

As indicated in FIGS. 1 and 2A, the package structure 100 of an embodiment of the present disclosure includes a package substrate 10, a chipset 80 to an encapsulant layer 50. In the present embodiment, the package substrate 10 may include a base layer 11, a plurality of through holes (via hole) 31, a first metal layer 13 and a second metal layer 14. The base layer 11 has a first surface 111 and a second surface 112 disposed oppositely. The through holes 31 penetrate through the base layer 11. The first metal layer 13 is disposed on the first surface 111 of the base layer 11. The second metal layer 14 is disposed on the second surface 112 of the base layer 11, and a part of the second metal layer 14 is electrically connected to the first metal layer 13 via through holes 31. The chipset 80 and the encapsulant layer 50 are disposed on the first metal layer 13.

As indicated in FIG. 1, the first metal layer 13 may be divided into an inner part and an outer part by a closed-loop trench 23. In the present embodiment, the through holes 31, the chipset 80 and the encapsulant layer 50 are positioned at the inner part of the closed-loop trench 23. Here, the inner part of the closed-loop trench 23 is defined as the space inside an outer sidewall 232 of the closed-loop trench 23. That is, the encapsulant layer 50 may fill up the closed-loop trench 23 without crossing over the outer sidewall 232 of the closed-loop trench 23. Besides, an inner part of the first metal layer 13 may be insulated from an outer part of the first metal layer 13 by the closed-loop trench 23. That is, the part of the first metal layer 13 inside the closed-loop trench 23 is insulated from the part of the first metal layer 13 outside the closed-loop trench 23 to avoid the inner part and the outer part of the first metal layer 13 from short-circuiting each other.

In an embodiment, the base layer 11 may be formed of a ceramic material, such as aluminum nitride or aluminum oxide. The first metal layer 13 and the second metal layer 14 may be realized by a copper layer. In some embodiments, the package substrate 10 may further include a plating layer (not illustrated) formed of such as gold or silver. The plating layer may be formed on the first metal layer 13 and the second metal layer 14 to avoid the first metal layer 13 and the second metal layer 14 from being vulcanized.

As indicated in FIGS. 1 and 2A, the package substrate 10 may have a plurality of separation structures 21 disposed on the first surface 111 of the base layer 11. For example, the separation structures 21 may be form by etching the first metal layer 13 to expose a part of the first surface 111 of the base layer 11. In the present embodiment, the chipset 80 is disposed on the separation structures 21, and the separation structures 21 are connected with the closed-loop trench 23.

In the present embodiment, the chipset 80 includes a plurality of chips 81. The distance between the chips 81 is such as 50 μm. Furthermore, the chips 81 may be realized by light-emitting diode chips formed on the first metal layer 13 in the form of flip chips, lateral chips, or vertical chips.

Although FIGS. 1 and 2A show that the chipset 80 includes 5 squared chips 81, the present disclosure is not limited thereto. In some embodiments, the chipset 80 may include only one single rectangular chip. If the chipset includes only one single chip, the single chip is free of pitch, and no dark area would be formed when the chipset works with other reflective elements and lens set to emit lights. That is, the shape and quantity of the chips included in the chipset may be adjusted according to the design needs.

In an embodiment, the width W of the closed-loop trench 23 may range from 80 to 300 μm, and the depth D of the closed-loop trench may be adjusted according to the thickness of the first metal layer 13. For example, the depth D of the closed-loop trench 23 may range from 40 to 80 μm. Here, the width W of the closed-loop trench 23 is defined as the distance between the inner sidewall 231 and the outer sidewall 232 of the closed-loop trench 23, and the depth D of the closed-loop trench 23 is defined as the depth of the closed-loop trench 23 along a direction perpendicular to the first surface 111 of the base layer 11 (Z direction). Moreover, the shortest distance S1 between the closed-loop trench 23 and the chipset 80 may range from 500 to 2000 μm.

Due to the design of the closed-loop trench 23 and the surface tension of the encapsulant layer 50, the encapsulant layer 50 may be controlled to fill up the closed-loop trench 23 without crossing over the outer sidewall 232 of the closed-loop trench 23 during the manufacturing process. Thus, the encapsulant layer 50 may be effectively prevented from overflowing to the area surrounded by the closed-loop trench 23 from the closed-loop trench 23. Furthermore, since the separation structures 21 disclosed in the embodiment of the present disclosure are connected with the closed-loop trench 23, the encapsulant layer 50 may fill up the separation structures 21 as well.

In an embodiment, the encapsulant layer 50 may be formed of transparent silicone or may include silicone and phosphor powder. As indicated in FIG. 2A, the encapsulant layer 50 may cover the chipset 80, but the present disclosure is not limited thereto.

In another embodiment of the present disclosure indicated in FIG. 2B, the encapsulant layer 50′ does not cover the chipset 80. That is, the encapsulant layer 50′ may be positioned on a lateral surface of the chipset 80 and a top surface of the chipset 80 may be exposed. In the present embodiment, a wavelength conversion layer 93 may be formed on the top surface of the chipset 80. For example, the wavelength conversion layer 93 may be formed on the top surface of the chipset 80 by way of spraying or mounting a phosphor film on the top surface. Since the wavelength conversion layer 93 uniformly formed on the top surface of the chipset 80 by way of spraying is thinner, the encapsulant layer 50′ may be thinned accordingly.

Besides, the encapsulant layer 50′ positioned on the lateral surface of the chipset 80 may include silicone and titanium dioxide (TiO₂), a viscosity of the encapsulant layer 50′ may range from 1000 to 20000 mPa·s, and a reflectivity of the encapsulant layer 50′ may range from 90% to 99%, such as 95%.

In an embodiment, the package structure 100 may include an electrostatic protection element 85 disposed on the first surface 111 of the base layer 11 for protecting the chipset 80 from damage.

FIG. 3A shows a bottom view of a package structure 100 of an embodiment of the present disclosure. FIG. 3B shows a bottom view of a package structure 100 of another embodiment of the present disclosure. That is, FIG. 1 shows a front structure of the package structure 100 of the embodiment of the present disclosure, and FIGS. 3A and 3B show a rear structure of the package structure 100 of the embodiment of the present disclosure.

In the present embodiment, the second metal layer 14 of the package substrate 10 may include a heat dissipation region 90, a anode region 141 and a cathode region 142 The heat dissipation region 90, the anode region 141 and the cathode region 142 are disposed on the second surface 112 of the base layer 11. The heat dissipation region 90 corresponds to the chipset 80. The anode region 141 and the cathode region 142 are separated from the heat dissipation region 90. The heat dissipation region 90 may conduct the heat generated by the chipset 80 to the outside of the chipset 80, but is not electrically connected to any elements.

The heat dissipation region 90 is formed of a plurality of trenches 91 arranged in a polygonal or curved array, and may be connected with the outside of the heat dissipation region 90. For example, the trenches 91 may form an array pattern composed of polygons such as triangles, squares, pentagons, or hexagons (as indicated in FIG. 3A). Or, the said array pattern composed of polygons may be replaced with a curved array pattern.

As indicated in FIG. 3A, due to the design of the plurality of trenches 91, the heat dissipation region 90 may be divided into a honeycomb-shaped pattern to facilitate the heat dissipation of the chipset 80. In the follow-up process, the package structure 100 may be coated with a solder paste containing a flux and connected with a circuit board. During the process of heating and connecting the package structure 100 to the circuit board, the solder paste containing the flux may generate gases which may form bubbles at soldering parts, and the soldering quality would deteriorate accordingly. Through the design of connecting the trenches 91 to the outside of the heat dissipation region 90, the generated bubbles may be discharged and the soldering quality may be effectively increased.

The anode region 141 and the cathode region 142 of the package substrate 10 are two parts of the second metal layer 14, and therefore may be electrically connected to the first metal layer 13 via the through holes 31.

Furthermore, the distance between the anode region 141 and the cathode region 142 of the package substrate 10, the distance between the anode region 141 and the heat dissipation region 90, and the distance between the cathode region 142 and the heat dissipation region 90 may be at least 400 μm. As indicated in FIG. 3A, the distance S2 between the anode region 141 and the cathode region 142 of the package substrate 10 is, for example, 400 μm.

The package structure of the present disclosure is not limited to the structure illustrated in FIG. 3A. FIG. 3B illustrates a rear structure of a package structure 100 of another embodiment of the present disclosure. In comparison to the structure illustrated in FIG. 3A, the structure illustrated in FIG. 3B has a larger heat dissipation region 90. Although the trenches 91 shown in FIGS. 3A and 3B both are arranged in an array pattern composed of hexagons, the present disclosure is not limited thereto. That is, the shape and quantity of the trenches 91 may be adjusted according to the design needs.

FIGS. 4A-4C show an embodiment of the manufacturing process of the package structure 100 of the present disclosure, wherein FIG. 4C shows, for example, a cross-sectional view of a package structure along a cross-sectional line B-B′ of FIG. 1 according to an embodiment of the present disclosure. It should be noted that some elements may be omitted in following drawings, such that the manufacturing process of the package substrate 100 can be clearly illustrated.

As indicated in FIG. 4A, a package substrate 10 is provided. Like the structure illustrated in FIG. 2B, the package substrate 10 of FIG. 4A may include a base layer 11, a first metal layer 13 and a second metal layer 14 The base layer 11 has a first surface 111 and a second surface 112 disposed oppositely, the first metal layer 13 is disposed on the first surface 111 and includes a closed-loop trench 23, and the second metal layer 14 is disposed on the second surface 112. Then, a chipset 80 is provided on (the first metal layer 13 of) the package substrate 10.

As indicated in FIG. 4B, a wavelength conversion layer 93 is formed on a surface of the chipset 80. In the present embodiment, the wavelength conversion layer 93 may cover the chipset 80. For example, the wavelength conversion layer 93 may be formed on the surface of the chipset 80 by way of spraying.

Lastly, an encapsulant layer 50 is formed on (the first metal layer 13 of) the package substrate 10. As indicated in FIG. 4C, the chipset 80 to the encapsulant layer 50 both are positioned at the inner part of the closed-loop trench 23, and the encapsulant layer 50 is positioned on the lateral surface of the wavelength conversion layer 93 and the chipset 80 only, and a part of the top surface of the wavelength conversion layer 93 is exposed.

However, the embodiment of the manufacturing process of the package structure 100 of the present disclosure is not limited thereto. FIGS. 4D-4E show another embodiment of the manufacturing process of the package structure 100 of the present disclosure, wherein FIG. 4E shows, for example, a cross-sectional view of a package structure along the cross-sectional line B-B′ of FIG. 1 according to another embodiment of the present disclosure. Similarly, some elements may be omitted in following drawings, such that the manufacturing process of the package substrate 100 can be clearly illustrated.

The step shown in FIG. 4D continues with of the step shown in FIG. 4A. As indicated in FIG. 4D, a wavelength conversion layer 93′ is formed on a top surface of the chipset 80. For example, the wavelength conversion layer 93′ may be mounted on the top surface of the chipset 80.

Lastly, as indicated in FIG. 4E, an encapsulant layer 50 is provided on the lateral surfaces of the chipset 80 and the wavelength conversion layer 93′. The encapsulant layer 50 is positioned at the inner part of the closed-loop trench 23, and the top surface of the wavelength conversion layer 93′ is exposed.

As disclosed in the above embodiments of the present disclosure, through the design of forming the closed-loop trench 23 on the front side and forming the heat dissipation region 90 on the rear side of the package substrate 10, respectively, overflow of resin can be effectively avoided and the soldering quality can be greatly increased.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the present disclosure being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A package substrate, comprising: a base layer; a plurality of through holes penetrating through the base layer; a first metal layer disposed on an upper surface and comprising an encircling portion and a plurality of upper pads arranged separately, wherein the encircling portion surrounds the upper pads to form a trench between the encircling portion and the upper pads, and at least one gap between the upper pads intercommunicates with the trench; and a second metal layer disposed on the lower surface comprising a plurality of bottom pads arranged separately, wherein the bottom pads are electrically connected to the upper pads via the through holes; wherein the encircling portion of the first metal layer is electrically floating.
 2. The package substrate according to claim 1, wherein the second metal layer further comprises: at least one heat dissipation pad corresponding to the upper pads and electrically insulated from the bottom pads.
 3. The package substrate according to claim 2, wherein the bottom pads of the second metal layer are divided into an anode region and a cathode region and surround the heat dissipation pad.
 4. The package substrate according to claim 2, wherein the heat dissipation pad are electrically floating.
 5. A package structure, comprising: a package substrate, comprising: a base layer; a plurality of through holes penetrating through the base layer; a first metal layer disposed on an upper surface and comprising an encircling portion and a plurality of upper pads arranged separately, wherein the encircling portion surrounds the upper pads to form a trench between the encircling portion and the upper pads, and at least one gap between the upper pads intercommunicates with the trench; and a second metal layer disposed on a lower surface comprising a plurality of bottom pads arranged separately, wherein the bottom pads are electrically connected to the upper pads via the through holes, and the encircling portion of the first metal layer is electrically floating; at least one chip disposed on the package substrate and electrically connected to the upper pads; a reflective layer disposed on the package substrate and having a portion filled into the trench, wherein the reflective layer covers the chip and exposes at least a portion of an upper surface of the chip; and a light transmissive layer covering the exposed portion of the upper surface of the chip.
 6. The package structure according to claim 5, wherein the second metal layer further comprising: at least one heat dissipation pad corresponding to the chip and electrically insulated from the bottom pads.
 7. The package structure according to claim 6, wherein the bottom pads of the second metal layer are divided into an anode region and a cathode region and surround the heat dissipation pad.
 8. The package structure according to claim 6, wherein the heat dissipation pad is electrically floating.
 9. The package structure according to claim 5, wherein the light transmissive layer comprises a wavelength conversion layer.
 10. The package substrate according to claim 5, wherein the reflective layer extends not beyond an outer wall of the trench.
 11. The package structure according to claim 5, wherein the package substrate further comprises: a plating layer formed on at least one of the first metal layer and the second metal layer, wherein the plating layer is formed of gold or silver.
 12. A package structure, comprising: a package substrate, comprising: a base layer; a plurality of through holes penetrating through the base layer; a first metal layer disposed on an upper surface and comprising an encircling portion and a plurality of upper pads arranged separately, wherein the encircling portion surrounds the upper pads to form a trench between the encircling portion and the upper pads, and at least one gap between the upper pads intercommunicates with the trench; and a second metal layer disposed on a lower surface comprising a plurality of bottom pads arranged separately, wherein the bottom pads are electrically connected to the upper pads via the through holes, and the encircling portion of the first metal layer is electrically floating; at least one chip disposed on the package substrate and electrically connected to the upper pads; a reflective layer disposed on the package substrate and having a portion filled into the trench, wherein the reflective layer surrounds a lateral surface of the chip and exposes at least a portion of an upper surface of the chip; and a light transmissive layer covering the exposed portion of the upper surface of the chip and at least extending between the reflective layer and the lateral surface of the chip.
 13. The package structure according to claim 12, wherein the second metal layer further comprising: at least one heat dissipation pad corresponding to the chip and electrically insulated from the bottom pads.
 14. The package structure according to claim 13, wherein the bottom pads of the second metal layer are divided into an anode region and a cathode region and surround the heat dissipation pad.
 15. The package structure according to claim 13, wherein the heat dissipation pad is electrically floating.
 16. The package structure according to claim 12, wherein the light transmissive layer comprises a wavelength conversion layer.
 17. The package substrate according to claim 12, wherein the reflective layer extends not beyond an outer wall of the trench.
 18. The package structure according to claim 12, wherein the package substrate further comprises: a plating layer formed on at least one of the first metal layer and the second metal layer; wherein the plating layer is formed of gold or silver. 